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Deposits and ore mineralization associated with Ophiolite Complexes in the Sudetes Mts. (Poland)
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
W. Olszyński, S.Z. Mikulski, S. Speczik
Podiform chromite deposits occurs within Gogołów-Jordanów and Braszowice-Brzeznica Ophiolites (localition no. 1 and 12 on Fig. 1). Chromite mineralization occurs within the top of the lower member of the ophiolite suite. The Tapadla deposit podiform chromites occurs in the Gogołów-Jordanów Ophiolite. This deposit consists of 13 lens-like ore bodies from 30-100 m long. Ore bodies are situated within dunite zones that occasionally occur in the serpentinized rocks. Four stages of serpentinization and carbonate metasomatism and chloritization have been distinguished. In the chromite ores three main structural types were observed: massive, pisolitic and disseminated. Chromite ores are high-Al type (A12O > 25 %). The ore bodies consist of fresh chromite grains. In some of ore lenses chromite is replaced by ferrichromite and magnetite rims. Chromites and ferrichromite rims may contain pentlandite inclusions. The chromite ores in the Tapadla and in Braszowice-Brzeznica ophiolite have similar features. Geometry of the ore bodies in the last area is still not established. The Ni-PGE mineralization was encountered in serpentinites in the Naslawice Quarry (no. 16; Fig. 1). This serpentinite represents ultramafic cumulates and consist mainly of serpentinite minerals (antigorite, chrisotile, lizardite), tremolite, Crspinels, magnetite and relicts of olivines.
Petrology, geochemistry and a probable late Cambrian age for harzburgites of the Coolac Serpentinite, New South Wales, Australia
Published in Australian Journal of Earth Sciences, 2018
Harzburgites and dunites that occur within the contact zone of the North Mooney Complex and its satellite bodies are fine-grained, greenish black in colour and completely serpentinised. Serpentine minerals are a mesh work of lizardite interspersed with patches of antigorite with or without veins of chrysotile. A remnant magnetite network marking the triple junctions of former olivine crystals is retained. Cr-spinel occurs as anhedral grains and is usually isotropic although some grains are reddish-brown in colour. Cr# recorded in these spinels have values of 0.49–0.58 with a similar range in Mg# (0.52–0.62). TiO2 content is relatively high (0.24–0.45 wt%).
Material study of green stone artifacts from a Teotihuacan complex
Published in Materials and Manufacturing Processes, 2020
M.D. Manrique-Ortega, A. Mitrani, E. Casanova-González, G. Pérez-Ireta, M.A. García-Bucio, I. Rangel-Chávez, V. Aguilar-Melo, O.G. de Lucio, J.L. Ruvalcaba-Sil, N. Sugiyama, S. Sugiyama
Three objects were classified within the serpentine group (PC03, PC05 and PC01) with bands at 471 cm−1 (δ Si – O–Si, Mg–O), 565 cm−1 (ω o τ Mg–O/Si–O), 645 cm−1 (γ Mg–OH), 992 and 1047 cm−1 (δ Si–O) (Fig. 6.b).[43,44] The serpentine group consists of a set of more than 20 amphiboles, of which antigorite, lizardite and chrysotile are the three most representative variants. Although infrared absorption spectroscopy can distinguish between the main members of this group,[43] it is difficult to differentiate them, due to the lower spectral resolution associated with the FTIR reflection mode.
Investigation of the reduction roasting of saprolite ores in the Caron process: reaction mechanisms and reduction kinetics
Published in Mineral Processing and Extractive Metallurgy, 2021
It has been shown that the overall nickel recovery (through leaching of the product) from reduced serpentine (lizardite) is strongly affected by extent of dehydration, reduction, sintering and olivine recrystallisation. The rates and extents of these processes are functions of starting material, thermal history, temperature and time. In reduction roasting conditions these processes take place simultaneously making it difficult to determine the relative importance at various process conditions.